The present invention relates to a braking guide device for controlling the feeding velocity of a slide fastener chain on a sewing machine whereby the slide fastener chain is attached to an article, e.g. fabrics, plastic sheets, leathers and the like, to be used with the slide fastener chain as fastened thereto.
Slide fasteners either of a continuous length or a unit length are usually sewn to articles, such as fabrics, plastic sheets, leathers and the like, using a sewing machine. The sewing of the fasteners to the articles is performed with the so-called fastener stringer which is one separable half of the fastener or with a fastener chain formed by interengaging a pair of the opposing fastener stringers. The fastener chain or stringer is fed under the presser foot of the sewing machine together with the article which is overlaid by the fastener chain or stringer as the sewing machine feed is moved.
In the feeding of the fastener chain and the fabric article, their traveling velocity is desirably the same so that the phenomenon of puckering or waving does not take place. It is, however, generally difficult to obtain the same traveling velocity, and the finished fabrics or cloths having the slide fastener chain sewed thereon tend to suffer from puckering or waving. Such difficulty may be obviated only by the skill of workers or operators who control the traveling velocity of the fabric or article by either acceleration or retardation of the sewing machine or alternately by hand, aided by their perceptional feeling.
Such manually accelerating or retardating operation may result in a tolerable matching of the traveling velocity when the properties of the carrier tape of the fastener chain and the article are closely similar to each other. However, if the properties widely differ from each other, for example, the article being a shaggy or fuzzy corduroy, very elastic knit cloth, leather- fur or the like, it is very difficult to obtain conformity between the traveling velocity of one and that of the other by mere manual control. Particularly, when the article to which the fastener chain is to be sewed is a shaggy cloth, the traveling of the fastener tape is badly disturbed and the waving of the finished article or puckering of the fastener chain is unavoidable. A usual way to solve this problem is that braking action is given to the fastener chain to produce frictional resistance during the traveling of the fastener chain under the presser foot of the sewing machine.
One of the known means for producing frictional resistance to the fastener chain is to provide a braking device on the route of travel of the continous fastener chain from a magazine containing the fastener chain in a reeled form to the presser foot of the sewing machine, so that the traveling velocity of the fastener chain is retarded by depressing the spring of the braking device. Alternatively, a special type of the presser foot of a sewing machine is known which is equipped integrally with a braking device at the inlet side of the fastener chain (see, for example, U.S. Pat. No. 2,329,991 and Japanese Patent Disclosure No. 47-46050).
The above-described means for imparting frictional resistance to the fastener chain is utilized only when the fastener chain is of a continous lengthy form. This is because, once the leading end of the fastener chain is inserted into the braking device, the traveling fastener chain is continuously under friction in the subsequent sewing. On the other hand, when the fastener chain is of a unit product length, it is required to insert and pull each fastener chain individually into or through the braking device, resulting in markedly reduced efficiency in the sewing work.